Vapor phase growth apparatus and vapor phase growth method

ABSTRACT

A vapor phase growth apparatus according to an embodiment includes, n reactors performing a deposition process for a plurality of substrates at the same time, a first main gas supply path distributing a predetermined amount of first process gas including a group-III element to the n reactors at the same time, a second main gas supply path distributing a predetermined amount of second process gas including a group-V element to the n reactors at the same time, a controller controlling a flow rate of the first and second process gas, on the basis of control values of the flow rates of the first and second process gas supplied to the n reactors, and independently controlling predetermined process parameter independently set for each of the n reactors on the basis of control values, rotary drivers, and a heater.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Applications No. 2015-168860, filed on Aug. 28, 2015,the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a vapor phase growth apparatus and avapor phase growth method that supply gas to form a film.

BACKGROUND OF THE INVENTION

As a method for forming a high-quality semiconductor film, there is anepitaxial growth technique which grows a single-crystal film on asubstrate, such as a wafer, using vapor phase growth. In a vapor phasegrowth apparatus using the epitaxial growth technique, a wafer is placedon a support portion in a reactor which is maintained at normal pressureor reduced pressure. Then, process gas, such as source gas which will bea raw material for forming a film, is supplied from an upper part of thereactor to the surface of the wafer in the reactor while the wafer isbeing heated. For example, the thermal reaction of the source gas occursin the surface of the wafer and an epitaxial single-crystal film isformed on the surface of the wafer.

In recent years, as a material forming alight emitting device or a powerdevice, a gallium nitride (GaN)-based semiconductor device has drawnattention. Metal organic chemical vapor deposition (MOCVD) method is anepitaxial growth technique that can form a GaN-based semiconductor film.In the organic metal vapor phase growth method, organic metal, such astrimethylgallium (TMG), trimethylindium (TMI), or trimethylaluminum(TMA), or ammonia (NH₃) is used as the source gas.

JP H10-158843A and JP 2002-212735A disclose a vapor phase growthapparatus that includes a plurality of reactors in order to improveproductivity. In addition, JP 2003-49278A discloses a method thatchanges the pressure control value of a reactor caused a trouble whenfilms are grown in a plurality of reactors.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a vapor phasegrowth apparatus including: n (n is an integer equal to or greater than2) reactors performing a deposition process for a plurality ofsubstrates at the same time; a first main gas supply path distributing apredetermined amount of first process gas including a group-III elementand supplying the first process gas to the n reactors at the same time;a second main gas supply path distributing a predetermined amount ofsecond process gas including a group-V element and supplying the secondprocess gas to the n reactors at the same time; a controller controllinga flow rate of the first process gas and a flow rate of the secondprocess gas, on the basis of control values of flow rates of the firstprocess gas and the second process gas supplied to the n reactors, thecontroller independently controlling at least one predetermined processparameter in the n reactors, on the basis of control values of the atleast one predetermined process parameter independently set for each ofthe n reactors; a rotary driver provided in each of the n reactors androtating each of the plurality of substrates; and a heater provided ineach of the n reactors and heating each of the plurality of substrates.

According to another aspect of the invention, there is provided a vaporphase growth method including: loading a plurality of substrates to nreactors; distributing a predetermined amount of first process gasincluding a group-III element and starting the first process gas supplyto the n reactors at the same time at a flow rate controlled on thebasis of control values of a first flow rate; distributing apredetermined amount of second process gas including a group-V elementand starting second process gas supply to the n reactors at the sametime at a flow rate controlled on the basis of control values of asecond flow rate; controlling independently at least one predeterminedprocess parameter of the n reactors, on the basis of control values ofthe at least one predetermined process parameter, and growing films onthe plurality of substrates in the n reactors at the same time; shuttingoff the first process gas supply to the n reactors at the same time; andshutting off the second process gas to the n reactors at the same time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the structure of a vapor phase growthapparatus according to a first embodiment;

FIG. 2 is a cross-sectional view schematically illustrating a reactor ofthe vapor phase growth apparatus according to the first embodiment;

FIG. 3 is a diagram illustrating the function and effect of the firstembodiment;

FIG. 4 is a diagram illustrating the function and effect of the firstembodiment;

FIG. 5 is a diagram illustrating the function and effect of the firstembodiment;

FIG. 6 is a diagram illustrating the structure of a vapor phase growthapparatus according to a second embodiment; and

FIG. 7 is a cross-sectional view schematically illustrating a reactor ofa vapor phase growth apparatus according to a third embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the drawings.

In the specification, the direction of gravity in a state in which avapor phase growth apparatus is provided so as to form a film is definedas a “lower” direction and a direction opposite to the direction ofgravity is defined as an “upper” direction. Therefore, a “lower portion”means a position in the direction of gravity relative to the referenceand a “lower side” means the direction of gravity relative to thereference. In addition, an “upper portion” means a position in thedirection opposite to the direction of gravity relative to the referenceand an “upper side” means the direction opposite to the direction ofgravity relative to the reference. Furthermore, a “longitudinaldirection” is the direction of gravity.

In the specification, “process gas” is a general term of gas used toform a film on a substrate. The concept of the “process gas” includes,for example, source gas, carrier gas, and diluent gas.

First Embodiment

A vapor phase growth apparatus according to this embodiment includes, n(n is an integer equal to or greater than 2) reactors performing adeposition process for a plurality of substrates at the same time, afirst main gas supply path distributing a predetermined amount of firstprocess gas including a group-III element and supplying the firstprocess gas to the n reactors at the same time, a second main gas supplypath distributing a predetermined amount of second process gas includinga group-V element and supplying the second process gas to the n reactorsat the same time, a controller controlling a flow rate of the firstprocess gas and a flow rate of the second process gas, on the basis ofcontrol values of the flow rates of the first process gas and the secondprocess gas supplied to the n reactors, and independently controllingpredetermined process parameters that are independently set for each ofthe n reactors, on the basis of control values of the predeterminedprocess parameters, rotary drivers provided in each of the n reactorsand rotating each of the plurality of substrates, and heaters providedin each of the n reactors and heating the plurality of substrates.

A vapor phase growth method according to this embodiment includes,loading a plurality of substrates to n reactors, distributing apredetermined amount of first process gas including a group-III elementand starting the first process gas supply to the n reactors at a flowrate that is controlled on the basis of a control value of a first flowrate at the same time, distributing a predetermined amount of secondprocess gas including a group-V element and starting the second processgas supply to the n reactors at a flow rate that is controlled on thebasis of a control value of a second flow rate at the same time,independently controlling predetermined process parameters of the nreactors, on the basis of control values of the predetermined processparameters of the n reactors, and growing films on the plurality ofsubstrates in the n reactors at the same time, shutting off the firstprocess gas supply to the n reactors at the same time, and shutting offthe second process gas supply to the n reactors at the same time.

According to the vapor phase growth apparatus and the vapor phase growthmethod having the above-mentioned structure according to thisembodiment, when films are formed on substrates in a plurality ofreactors at the same time, it is possible to adjust the characteristicsof the films grown in each reactor. The characteristics of the film are,for example, the thickness or composition of the film.

FIG. 1 is a diagram illustrating the structure of the vapor phase growthapparatus according to this embodiment. The vapor phase growth apparatusaccording to this embodiment is an epitaxial growth apparatus using ametal organic chemical vapor deposition (MOCVD) method.

The vapor phase growth apparatus according to this embodiment includesfour reactors 10 a, 10 b, 10 c, and 10 d. Each of the four reactors 10a, 10 b, 10 c, and 10 d is, for example, a vertical single-wafer-typeepitaxial growth apparatus. The number of reactors is not limited to 4and two or more reactors may be used. The number of reactors can berepresented by n (n is an integer equal to or greater than 2).

The vapor phase growth apparatus according to this embodiment includes afirst main gas supply path 11, a second main gas supply path 21, and athird main gas supply path 31 which supply process gas to the fourreactors 10 a, 10 b, 10 c, and 10 d.

The first main gas supply path 11 supplies, for example, a first processgas including organic metal, which is a group III element, and carriergas to the reactors 10 a, 10 b, 10 c, and 10 d. The first process gas isgas including a group-III element when a group III-V semiconductor filmis formed on a wafer. The first main gas supply path 11 distributes andsupplies a predetermined amount of first process gas including agroup-III element to the four reactors 10 a, 10 b, 10 c, and 10 d at thesame time.

The group-III element is, for example, gallium (Ga), aluminum (Al), orindium (In). In addition, the organic metal is, for example,trimethylgallium (TMG), trimethylaluminum (TMA), or trimethylindium(TMI).

The carrier gas is, for example, hydrogen gas. Only the hydrogen gas mayflow through the first main gas supply path 11.

A first main mass flow controller 12 is provided in the first main gassupply path 11. The first main mass flow controller 12 controls the flowrate of the first process gas that flows through the first main gassupply path 11.

In addition, the first main gas supply path 11 is branched into threefirst sub-gas supply paths 13 a, 13 b, and 13 c and one second sub-gassupply path 13 d at a position that is closer to the reactors 10 a, 10b, 10 c, and 10 d than to the first main mass flow controller 12. Thefirst sub-gas supply paths 13 a, 13 b, and 13 c and the second sub-gassupply path 13 d supply the distributed first process gases to the fourreactors 10 a, 10 b, 10 c, and 10 d, respectively.

A first manometer 41 is provided in the first main gas supply path 11.The first manometer 41 is provided between the first main mass flowcontroller 12 and the position where the first main gas supply path 11is branched into the three first sub-gas supply paths 13 a, 13 b, and 13c and the one second sub-gas supply path 13 d. The first manometer 41monitors the pressure of the first main gas supply path 11.

First sub-mass flow controllers 14 a, 14 b, and 14 c are provided in thethree first sub-gas supply paths 13 a, 13 b, and 13 c, respectively. Thefirst sub-mass flow controllers 14 a, 14 b, and 14 c control the flowrate of the first process gas that flows through the first sub-gassupply paths 13 a, 13 b, and 13 c, respectively. The first sub-mass flowcontrollers 14 a, 14 b, and 14 c are a flow rate control type.

A fourth sub-mass flow controller 14 d of an opening position controltype is provided in the one second sub-gas supply path 13 d. The secondsub-gas supply path 13 d supplies the first process gas to one reactor10 d other than three reactors 10 a, 10 b, and 10 c to which the firstsub-gas supply paths 13 a, 13 b, and 13 c supply the first process gas,respectively. In the total amount of first process gas supplied from thefirst main gas supply path 11, the remainder of the first process gaswhich does not flow through the first sub-gas supply paths 13 a, 13 b,and 13 c flows from the second sub-gas supply path 13 d to the reactor10 d.

Specifically, the degree of opening of the fourth sub-mass flowcontroller 14 d is controlled on the basis of the measurement result ofthe pressure of the first main gas supply path 11 monitored by the firstmanometer 41. For example, the degree of opening of the fourth sub-massflow controller 14 d is controlled such that the pressure monitored bythe first manometer 41 is zero. According to this structure, in thetotal amount of first process gas supplied from the first main gassupply path 11, the remainder of the first process gas which does notflow through the first sub-gas supply paths 13 a, 13 b, and 13 c canflow from the second sub-gas supply path 13 d to the reactor 10 d.

For example, the second main gas supply path 21 supplies a secondprocess gas including ammonia (NH₃) to the reactors 10 a, 10 b, 10 c,and 10 d. The second process gas is a source gas of a group-V elementand nitrogen (N) when a group III-V semiconductor film is formed on awafer. The second main gas supply path 21 distributes and supplies apredetermined amount of second process gas including a group-V elementto the four reactors 10 a, 10 b, 10 c, and 10 d at the same time.

Only hydrogen gas may flow through the second main gas supply path 21.

A second main mass flow controller 22 is provided in the second main gassupply path 21. The second main mass flow controller 22 controls theflow rate of the second process gas that flows through the second maingas supply path 21.

In addition, the second main gas supply path 21 is branched into threethird sub-gas supply paths 23 a, 23 b, and 23 c and one fourth sub-gassupply path 23 d at a position that is closer to the reactors 10 a, 10b, 10 c, and 10 d than to the second main mass flow controller 22. Thethird sub-gas supply paths 23 a, 23 b, and 23 c and the fourth sub-gassupply path 23 d supply the distributed second process gases to the fourreactors 10 a, 10 b, 10 c, and 10 d, respectively.

A second manometer 51 is provided in the second main gas supply path 21.The second manometer 51 is provided between the second main mass flowcontroller 22 and the position where the second main gas supply path 21is branched into the three third sub-gas supply paths 23 a, 23 b, and 23c and the one fourth sub-gas supply path 23 d. The second manometer 51monitors the pressure of the second main gas supply path 21.

Second sub-mass flow controllers 24 a, 24 b, and 24 c are provided inthe three third sub-gas supply paths 23 a, 23 b, and 23 c, respectively.The second sub-mass flow controllers 24 a, 24 b, and 24 c control theflow rate of the second process gas that flows through the third sub-gassupply paths 23 a, 23 b, and 23 c, respectively. The second sub-massflow controllers 24 a, 24 b, and 24 c are a flow rate control type.

A fifth sub-mass flow controller 24 d of an opening position controltype is provided in the one fourth sub-gas supply path 23 d. The fourthsub-gas supply path 23 d supplies the second process gas to one reactor10 d other than three reactors 10 a, 10 b, and 10 c to which the thirdsub-gas supply paths 23 a, 23 b, and 23 c supply the second process gas,respectively. In the total amount of second process gas supplied fromthe second main gas supply path 21, the remainder of the second processgas which does not flow through the third sub-gas supply paths 23 a, 23b, and 23 c flows from the fourth sub-gas supply path 23 d to thereactor 10 d.

Specifically, the degree of opening of the fifth sub-mass flowcontroller 24 d is controlled on the basis of the measurement result ofthe pressure of the second main gas supply path 21 monitored by thesecond manometer 51. For example, the degree of opening of the fifthsub-mass flow controller 24 d is controlled such that the pressuremonitored by the second manometer 51 is zero. According to thisstructure, in the total amount of second process gas supplied from thesecond main gas supply path 21, the remainder of the second process gaswhich does not flow through the third sub-gas supply paths 23 a, 23 b,and 23 c can flow from the fourth sub-gas supply path 23 d to thereactor 10 d.

The third main gas supply path 31 supplies a diluent gas which dilutesthe first process gas and the second process gas to the reactors 10 a,10 b, 10 c, and 10 d. The first process gas and the second process gasare diluted with the diluent gas to adjust the concentration of thegroup-III element and the group-V element supplied to the reactors 10 a,10 b, 10 c, and 10 d. The diluent gas is inert gas, such as hydrogengas, nitrogen gas, or argon gas, or a mixed gas thereof.

A third main mass flow controller 32 is provided in the third main gassupply path 31. The third main mass flow controller 32 controls the flowrate of the diluent gas that flows through the third main gas supplypath 31.

In addition, the third main gas supply path 31 is branched into threefifth sub-gas supply paths (diluent gas supply lines) 33 a, 33 b, and 33c and one sixth sub-gas supply path (diluent gas supply line) 33 d at aposition that is closer to the reactors 10 a, 10 b, 10 c, and 10 d thanto the third main mass flow controller 32. The fifth sub-gas supplypaths 33 a, 33 b, and 33 c and the sixth sub-gas supply path 33 d supplythe distributed diluent gases to the four reactors 10 a, 10 b, 10 c, and10 d, respectively. The three fifth sub-gas supply paths and the onesixth sub-gas supply path are an example of four diluent gas supplylines.

A third manometer 61 is provided in the third main gas supply path 31.The third manometer 61 is provided between the third main mass flowcontroller 32 and the position where the third main mass flow controller32 is branched into the three fifth sub-gas supply paths 33 a, 33 b, and33 c and the one sixth sub-gas supply path 33 d. The third manometer 61monitors the pressure of the third main gas supply path 31.

Third sub-mass flow controllers 34 a, 34 b, and 34 c are provided in thethree fifth sub-gas supply paths 33 a, 33 b, and 33 c, respectively. Thethird sub-mass flow controllers 34 a, 34 b, and 34 c control the flowrate of the diluent gas that flows through the fifth sub-gas supplypaths 33 a, 33 b, and 33 c, respectively. The third sub-mass flowcontrollers 34 a, 34 b, and 34 c are a flow rate control type.

A sixth sub-mass flow controller 34 d of an opening position controltype is provided in the one sixth sub-gas supply path 33 d. The sixthsub-gas supply path 33 d supplies the diluent gas to one reactor 10 dother than three reactors 10 a, 10 b, and 10 c to which the fifthsub-gas supply paths 33 a, 33 b, and 33 c supply the diluent gas,respectively. In the total amount of diluent gas supplied from the thirdmain gas supply path 31, the remainder of the diluent gas which does notflow through the fifth sub-gas supply paths 33 a, 33 b, and 33 c flowsfrom the sixth sub-gas supply path 33 d to the reactor 10 d.

Specifically, the degree of opening of the sixth sub-mass flowcontroller 34 d is controlled on the basis of the measurement result ofthe pressure of the third main gas supply path 31 monitored by the thirdmanometer 61. For example, the degree of opening of the sixth sub-massflow controller 34 d is controlled such that the pressure monitored bythe third manometer 61 is zero. According to this structure, in thetotal amount of diluent gas supplied from the third main gas supply path31, the remainder of the diluent gas which does not flow through thefifth sub-gas supply paths 33 a, 33 b, and 33 c can flow from the sixthsub-gas supply path 33 d to the reactor 10 d.

Four adjustment gas supply paths 131 a, 131 b, 131 c, and 131 d areconnected to the fifth sub-gas supply paths 33 a, 33 b, and 33 c and thesixth sub-gas supply path 33 d, respectively. The adjustment gas supplypaths 131 a, 131 b, 131 c, and 131 d are connected to the fifth sub-gassupply paths 33 a, 33 b, and 33 c and the sixth sub-gas supply path 33 dat the positions that are closer to the reactors 10 a, 10 b, 10 c, and10 d than to the third sub-mass flow controllers 34 a, 34 b, and 34 cand the sixth sub-mass flow controller 34 d, respectively.

The adjustment gas supply paths 131 a, 131 b, 131 c, and 131 d supplythe diluent gas to the fifth sub-gas supply paths 33 a, 33 b, and 33 cand the sixth sub-gas supply path 33 d, respectively. Inert gas, such ashydrogen gas, nitrogen gas, or argon gas, is supplied to the adjustmentgas supply paths 131 a, 131 b, 131 c, and 131 d.

Adjustment mass flow meters 134 a, 134 b, 134 c, and 134 d are providedin the adjustment gas supply paths 131 a, 131 b, 131 c, and 131 d,respectively. The adjustment mass flow meters 134 a, 134 b, 134 c, and134 d adjust the amount of diluent gas supplied to the fifth sub-gassupply paths 33 a, 33 b, and 33 c and the sixth sub-gas supply path 33d, respectively. The adjustment mass flow meters 134 a, 134 b, 134 c,and 134 d are, for example, a flow rate control type.

The adjustment gas supply paths 131 a, 131 b, 131 c, and 131 dindependently adjust the flow rate of the diluent gas supplied to thereactors 10 a, 10 b, 10 c, and 10 d. The concentration of the group-IIIelement and the group-V element in the process gas supplied to thereactors can be independently adjusted by the adjustment gas supplypaths 131 a, 131 b, 131 c, and 131 d.

The vapor phase growth apparatus according to this embodiment includesfour sub-gas exhaust paths 15 a, 15 b, 15 c, and 15 d through which gasis discharged from the four reactors 10 a, 10 b, 10 c, and 10 d. Inaddition, the vapor phase growth apparatus includes a main gas exhaustpath 16 that is connected to the four sub-gas exhaust paths 15 a, 15 b,15 c, and 15 d. A vacuum pump 17 for drawing gas is provided in the maingas exhaust path 16. The vacuum pump 17 is an example of a pump.

In addition, the vapor phase growth apparatus according to thisembodiment includes a controller 19. The controller 19 controls the flowrate of the first process gas and the flow rate of the second processgas, on the basis of the control values of the flow rates of the firstprocess gas and the second process gas supplied to the four reactors 10a, 10 b, 10 c, and 10 d. Furthermore, the controller 19 independentlycontrols predetermined process parameters which are independently setfor the four reactors 10 a, 10 b, 10 c, and 10 d, on the basis of thecontrol values of the predetermined process parameters.

The controller 19 can control the control values of the processparameters of the four reactors 10 a, 10 b, 10 c, and 10 d under thesame conditions, that is, in the same process recipe, at the same time.In addition, the controller 19 performs control such that fouroperations, that is, a first process gas supply start operation, a firstprocess gas supply shut off operation, a second process gas supply startoperation, and a second process gas supply shut off operation areperformed in the four reactors 10 a, 10 b, 10 c, and 10 d at the sametime.

The controller 19 can perform control such that the control values ofthe predetermined process parameters of the four reactors 10 a, 10 b, 10c, and 10 d are independently set for the four reactors 10 a, 10 b, 10c, and 10 d and films are grown on the substrates at the same time inthe four reactors 10 a, 10 b, 10 c, and 10 d, in order to match thecharacteristics of the films formed in the four reactors 10 a, 10 b, 10c, and 10 d.

The predetermined process parameters which can be independently set areat least one of the control values of the concentration of the group-IIIelement and the group-V element supplied to the reactors, the rotationspeed of the substrate, the temperature of the substrate, and an outputfrom a heater.

The controller 19 includes a calculator 19 a. The calculator 19 a has afunction of calculating the control values of the predetermined processparameters from information about the correlation between thecharacteristics of the films obtained in advance in the four reactors 10a, 10 b, 10 c, and 10 d and the predetermined process parameters and thecharacteristics of the films obtained in advance in the four reactors 10a, 10 b, 10 c, and 10 d.

The controller 19 is, for example, a controller. The controller is, forexample, hardware or a combination of hardware and software.

The controller 19 controls the amount of diluent gas supplied, on thebasis of, for example, the control value of the concentration of thegroup-III element and the group-V element independently set for each ofthe four reactors 10 a, 10 b, 10 c, and 10 d.

FIG. 2 is a cross-sectional view schematically illustrating the reactorof the vapor phase growth apparatus according to this embodiment. FIG. 2illustrates one of the four reactors 10 a, 10 b, 10 c, and 10 d, forexample, the reactor 10 a. The four reactors 10 a, 10 h, 10 c, and 10 dhave the same structure.

As illustrated in FIG. 2, the reactor 10 a according to this embodimentincludes, for example, a wall surface 100 of a stainless cylindricalhollow body. A shower plate 101 is provided in an upper part of thereactor 10 a. The shower plate 101 supplies the process gas into thereactor 10 a.

The reactor 10 a includes a support portion 112. A semiconductor wafer(substrate) W can be placed on the support portion 112. The supportportion 112 is, for example, an annular holder that has an openingformed at the center thereof or a susceptor without an opening.

The first sub-gas supply path 13 a, the third sub-gas supply path 23 a,and the fifth sub-gas supply path 33 a are connected to the shower plate101. A plurality of gas ejection holes for ejecting the first processgas, the second process gas, and the diluent gas which are mixed in theshower plate 101 into the reactor 10 a are provided in the surface ofthe shower plate 101 close to the reactor 10 a.

The reactor 10 a includes a rotary driver 114. The support portion 112is provided above the rotary driver 114.

In the rotary driver 114, a rotating shaft 118 is connected to a rotarydriver 120. The rotary driver 120 can rotate the semiconductor wafer Wplaced on the support portion 112 at a speed that is, for example, equalto or greater than 50 rpm and equal to or less than 3000 rpm. The rotarydriver 120 is, for example, a motor.

The rotary driver 114 includes a heater 116 that heats the wafer Wplaced on the support portion 112. The heater 116 is, for example, aheater.

The heater 116 is provided in the rotary driver 114 so as to be fixed.Power is supplied to the heater 116 through an electrode 122 that passesthrough the rotating shaft 118 to control the output of the heater 116from 0% to 100%. In addition, a push up pin (not illustrated) thatpasses through the heater 116 is provided in order to attach or detachthe semiconductor wafer W to or from the support portion 112.

A gas discharge portion 126 is provided at the bottom of the reactor 10a. The gas discharge portion 126 discharges a reaction product obtainedby the reaction of source gas on the surface of the semiconductor waferW and the process gas remaining in the reactor 10 a to the outside ofthe reactor 10 a. The gas discharge portion 126 is connected to thesub-gas exhaust path 15 a (FIG. 1).

A wafer inlet and a gate valve (not illustrated) are provided in thewall surface 100 of the reactor 10 a. The semiconductor wafer W can beloaded to or unloaded from the reactor 10 a by the wafer inlet and thegate valve.

A vapor phase growth method according to this embodiment uses theepitaxial growth apparatus illustrated in FIGS. 1 and 2. Next, the vaporphase growth method according to this embodiment will be described. Anexample in which a stacked film obtained by stacking a plurality offirst nitride semiconductor films including indium (In) and gallium (Ga)and a plurality of second nitride semiconductor films including gallium(Ga) is formed on a GaN film will be described. The first nitridesemiconductor film and the second nitride semiconductor film aresingle-crystal films which are formed by epitaxial growth. The stackedfilm is, for example, a multi-quantum well (MQW) layer of a lightemitting diode (LED).

In the vapor phase growth method according to this embodiment, first, avariation in the characteristics of a film which is formed on asubstrate for a test (test substrate) in each of the reactors 10 a, 10b, 10 c, and 10 d is evaluated. The characteristics of the film are thethickness and composition of the film. When a film is grown on the testsubstrate, the controller 19 controls the process parameters of the fourreactors 10 a, 10 b, 10 c, and 10 d with the same initial control value.

First, a semiconductor wafer W2, which is an example of the testsubstrate, is loaded to each of the four reactors 10 a, 10 b, 10 c, and10 d. GaN films are formed on a plurality of semiconductor wafers W2 inadvance.

An indium gallium nitride (InGaN) film and a gallium nitride (GaN) filmare alternately grown on the GaN film of the semiconductor wafer W2.When the InGaN film is formed, a mixed gas (first process gas) of TMGand TMI having, for example, nitrogen gas as carrier gas is suppliedfrom the first main gas supply path 11 to each of the four reactors 10a, 10 b, 10 c, and 10 d. In addition, for example, ammonia (secondprocess gas) is supplied from the second main gas supply path 21 to eachof the four reactors 10 a, 10 b, 10 c, and 10 d.

When the GaN film is formed on the semiconductor wafer W2, TMG (firstprocess gas) having, for example, nitrogen gas as carrier gas issupplied from the first main gas supply path 11 to each of the fourreactors 10 a, 10 b, 10 c, and 10 d. In addition, for example, ammonia(second process gas) is supplied from the second main gas supply path 21to each of the four reactors 10 a, 10 b, 10 c, and 10 d.

The first process gas, of which the flow rate has been controlled by thefirst main mass flow controller 12, flows to the first main gas supplypath 11. The first process gas is distributed and flows to the threefirst sub-gas supply paths 13 a, 13 b, and 13 c and the one secondsub-gas supply path 13 d which are branched from the first main gassupply path 11.

The flow rates of the first process gases distributed to the three firstsub-gas supply paths 13 a, 13 b, and 13 c are controlled by the firstsub-mass flow controllers 14 a, 14 b, and 14 c, respectively. Forexample, the flow rates of the first process gases controlled by thefirst sub-mass flow controllers 14 a, 14 b, and 14 c are set such that aquarter (¼) of the total amount of first process gas set by the firstmain mass flow controller 12 flows.

In addition, the degree of opening of the fourth sub-mass flowcontroller 14 d is controlled such that the pressure of the first maingas supply path 11 monitored by the first manometer 41 is zero. In thisway, the remainder of the first process gas which does not flow throughthe three first sub-gas supply paths 13 a, 13 b, and 13 c, that is, theamount of first process gas which corresponds to a quarter (¼) of thetotal amount of first process gas flows to the remaining one secondsub-gas supply path 13 d. The first process gases distributed from thefirst main gas supply path 11 to the three first sub-gas supply paths 13a, 13 b, and 13 c and the second sub-gas supply path 13 d are suppliedto the four reactors 10 a, 10 b, 10 c, and 10 d, respectively.

A predetermined amount of first process gas is distributed and thesupply of the first process gas to each of the four reactors 10 a, 10 b,10 c, and 10 d at a flow rate that is controlled on the basis of thecontrol value of a first flow rate starts at the same time.

The second process gas, of which the flow rate has been controlled bythe second main mass flow controller 22, flows to the second main gassupply path 21. Then, the second process gas is distributed and flows tothree third sub-gas supply paths 23 a, 23 b, and 23 c and one fourthsub-gas supply path 23 d which are branched from the second main gassupply path 21.

The flow rates of the second process gases distributed to the threethird sub-gas supply paths 23 a, 23 b, and 23 c are controlled by thesecond sub-mass flow controllers 24 a, 24 b, and 24 c, respectively. Forexample, the flow rates of the second process gases controlled by thesecond sub-mass flow controllers 24 a, 24 b, and 24 c are set such thata quarter (¼) of the total amount of second process gas set by thesecond main mass flow controller 22 flows.

In addition, the degree of opening of the fifth sub-mass flow controller24 d is controlled such that the pressure of the second main gas supplypath 21 monitored by the second manometer 51 is zero. In this way, theremainder of the second process gas which does not flow through thethree third sub-gas supply paths 23 a, 23 b, and 23 c, that is, theamount of second process gas which corresponds to a quarter (¼) of thetotal amount of second process gas flows to the remaining one fourthsub-gas supply path 23 d. The second process gases distributed from thesecond main gas supply path 21 to the three third sub-gas supply paths23 a, 23 b, and 23 c and the fourth sub-gas supply path 23 d aresupplied to the four reactors 10 a, 10 b, 10 c, and 10 d, respectively.

A predetermined amount of second process gas is distributed and thesupply of the second process gas to each of the four reactors 10 a, 10b, 10 c, and 10 d at a flow rate that is controlled on the basis of thecontrol value of a second flow rate starts at the same time.

When an InGaN film and a GaN film are alternately grown on the GaN filmof the semiconductor wafer W2, the controller 19 performs control suchthat four operations, that is, the first process gas supply startoperation, the first process gas supply shut off operation, the secondprocess gas supply start operation, and the second process gas supplyshut off operation are performed in the four reactors 10 a, 10 b, 10 c,and 10 d at the same time.

When an InGaN film and a GaN film are alternately grown on the GaN filmof the semiconductor wafer W2, the diluent gas is supplied from thethird main gas supply path 31 to the four reactors 10 a, 10 b, 10 c, and10 d on the basis of the same initial control value.

When an InGaN film and a GaN film are alternately grown on the GaN filmof the semiconductor wafer W2, the initial control values of threeprocess parameters, that is, the concentration of the group-III elementand the group-V element supplied to the four reactors 10 a, 10 b, 10 c,and 10 d, the rotation speed of the semiconductor wafer W2, and thetemperature of the semiconductor wafer W2 are set to the same value forthe four reactors 10 a, 10 b, 10 c, and 10 d and films are grown on aplurality of semiconductor wafers W2 in the four reactors 10 a, 10 b, 10c, and 10 d at the same time.

The control value of the concentration of the group-III element and thegroup-V element supplied to the four reactors 10 a, 10 b, 10 c, and 10 dis, for example, the flow rate control values of the first main massflow controller 12 and the second main mass flow controller 22. Thecontrol value of the rotation speed of the semiconductor wafer W2 is therotation number control value of the rotary driver 114. The controlvalue of the temperature of the semiconductor wafer W2 is, for example,the control value of power supplied to the heater 116.

The first process gas, the second process gas, and the diluent gas aresupplied to each of the reactors 10 a, 10 b, 10 c, and 10 d by theabove-mentioned method and a stacked film obtained by alternatelystacking the InGaN film and the GaN film is formed on the semiconductorwafer W2.

Then, the semiconductor wafers W2 are unloaded from the four reactors 10a, 10 b, 10 c, and 10 d and the characteristics of the films grown onthe semiconductor wafer W2 are measured. The characteristics of the filmare, for example, the thickness and composition of the film. Forexample, the thickness of the film can be measured on an image capturedby a transmission electron microscope (TEM). The composition of the filmcan be measured by, for example, a secondary ion mass spectrometry(SIMS).

In the subsequent process, when the same stacked film is grown, thecontrol values of the process parameters to be set are determined on thebasis of the characteristics of the films grown on the testsemiconductor wafer W2. The process parameters are the concentration ofthe group-III element and the group-V element supplied to the fourreactors 10 a, 10 b, 10 c, and 10 d, the rotation speed of thesemiconductor wafer W2, and the temperature of the semiconductor waferW2.

For example, the calculator 19 a of the controller 19 calculates thecontrol values of the concentration of the group-III element and thegroup-V element, the rotation speed of the semiconductor wafer W2, andthe temperature of the semiconductor wafer W2 from information about thecorrelation among the thickness and composition of the film obtained inadvance in each of the four reactors 10 a, 10 b, 10 c, and 10 d, theconcentration of the group-III element and the group-V element, therotation speed of the semiconductor wafer W2, and the temperature of thesemiconductor wafer W2 and the thickness and composition of the filmobtained from the semiconductor wafer W2.

The control values of the process parameters which are set for each ofthe reactors 10 a, 10 b, 10 c, and 10 d are set such that the filmsgrown in the reactors 10 a, 10 b, 10 c, and 10 d have the same thicknessand composition.

Then, a semiconductor wafer W1 which is an example of the substrate isloaded to each of the four reactors 10 a, 10 b, 10 c, and 10 d. A GaNfilm is formed on the semiconductor wafer W1 in advance.

An InGaN film and a GaN film are alternately grown on the GaN film ofthe semiconductor wafer W1. When the InGaN film is formed, a mixed gas(first process gas) of TMG and TMI having, for example, nitrogen gas ascarrier gas is supplied from the first main gas supply path 11 to eachof the four reactors 10 a, 10 b, 10 c, and 10 d. In addition, forexample, ammonia (second process gas) is supplied from the second maingas supply path 21 to each of the four reactors 10 a, 10 b, 10 c, and 10d.

When the GaN film is formed on the semiconductor wafer W1, TMG (firstprocess gas) having, for example, nitrogen gas as carrier gas issupplied from the first main gas supply path 11 to each of the fourreactors 10 a, 10 b, 10 c, and 10 d. In addition, for example, ammonia(second process gas) is supplied from the second main gas supply path 21to each of the four reactors 10 a, 10 b, 10 c, and 10 d.

The first process gas, of which the flow rate has been controlled by thefirst main mass flow controller 12, flows to the first main gas supplypath 11. The first process gas is distributed and flows to three firstsub-gas supply paths 13 a, 13 b, and 13 c and one second sub-gas supplypath 13 d which are branched from the first main gas supply path 11.

The flow rates of the first process gases distributed to the three firstsub-gas supply paths 13 a, 13 b, and 13 c are controlled by the firstsub-mass flow controllers 14 a, 14 b, and 14 c, respectively. Forexample, the flow rates of the first process gases controlled by thefirst sub-mass flow controllers 14 a, 14 b, and 14 c are set such that aquarter (¼) of the total amount of first process gas set by the firstmain mass flow controller 12 flows.

In addition, the degree of opening of the fourth sub-mass flowcontroller 14 d is controlled such that the pressure of the first maingas supply path 11 monitored by the first manometer 41 is zero. In thisway, the remainder of the first process gas which does not flow throughthe three first sub-gas supply paths 13 a, 13 b, and 13 c, that is, theamount of first process gas which corresponds to a quarter (¼) of thetotal amount of first process gas flows to the remaining one secondsub-gas supply path 13 d. The first process gases distributed from thefirst main gas supply path 11 to the three first sub-gas supply paths 13a, 13 b, and 13 c and the second sub-gas supply path 13 d are suppliedto the four reactors 10 a, 10 b, 10 c, and 10 d, respectively.

A predetermined amount of first process gas is distributed and thesupply of the first process gas to each of the four reactors 10 a, 10 b,10 c, and 10 d at a flow rate that is controlled on the basis of thecontrol value of a first flow rate starts at the same time.

The second process gas, of which the flow rate has been controlled bythe second main mass flow controller 22, flows to the second main gassupply path 21. Then, the second process gas is distributed and flows tothe three third sub-gas supply paths 23 a, 23 b, and 23 c and the onefourth sub-gas supply path 23 d which are branched from the second maingas supply path 21.

The flow rates of the second process gases distributed to the threethird sub-gas supply paths 23 a, 23 b, and 23 c are controlled by thesecond sub-mass flow controllers 24 a, 24 b, and 24 c, respectively. Forexample, the flow rates of the second process gases controlled by thesecond sub-mass flow controllers 24 a, 24 b, and 24 c are set such thata quarter (¼) of the total amount of second process gas set by thesecond main mass flow controller 22 flows.

In addition, the degree of opening of the fifth sub-mass flow controller24 d is controlled such that the pressure of the second main gas supplypath 21 monitored by the second manometer 51 is zero. In this way, theremainder of the second process gas which does not flow through thethree third sub-gas supply paths 23 a, 23 b, and 23 c, that is, theamount of second process gas which corresponds to a quarter (¼) of thetotal amount of second process gas flows to the remaining one fourthsub-gas supply path 23 d. The second process gases distributed from thesecond main gas supply path 21 to the three third sub-gas supply paths23 a, 23 b, and 23 c and the fourth sub-gas supply path 23 d aresupplied to the four reactors 10 a, 10 b, 10 c, and 10 d, respectively.

A predetermined amount of second process gas is distributed and thesupply of the second process gas to each of the four reactors 10 a, 10b, 10 c, and 10 d at a flow rate that is controlled on the basis of thecontrol value of a second flow rate starts at the same time.

When an InGaN film and a GaN film are alternately grown on the GaN filmof the semiconductor wafer W1, the controller 19 performs control suchthat four operations, that is, the first process gas supply startoperation, the first process gas supply shut off operation, the secondprocess gas supply start operation, and the second process gas supplyshut off operation are performed in the four reactors 10 a, 10 b, 10 c,and 10 d at the same time.

In addition, the control value of at least one process parameter that isselected from the concentration of the group-III element and the group-Velement supplied to the reactors 10 a, 10 b, 10 c, and 10 d, therotation speed of the semiconductor wafer W1, and the temperature of thesemiconductor wafer W1 is set for at least one of the four reactors 10a, 10 b, 10 c, and 10 d such that the control value is different fromthose set for the other reactors and films are grown on thesemiconductor wafers W1 in the four reactors 10 a, 10 b, 10 c, and 10 dat the same time.

The controller 19 independently sets and controls at least one processparameter among the concentration of the group-III element and thegroup-V element in the four reactors 10 a, 10 b, 10 c, and 10 d, therotation speed of the semiconductor wafer W1, and the temperature of thesemiconductor wafer W1, on the basis of the control values of theconcentration of the group-III element and the group-V element in thefour reactors 10 a, 10 b, 10 c, and 10 d, the rotation speed of thesemiconductor wafer W1, and the temperature of the semiconductor waferW1.

In this embodiment, the control values of the concentration of thegroup-III element and the group-V element, the rotation speed of thesemiconductor wafer W1, and the temperature of the semiconductor waferW1 which have been determined on the basis of the characteristics of thefilms grown on the test semiconductor wafer W2 are applied.

For example, when the control value of the concentration of thegroup-III element and the group-V element is set for a specific reactorsuch that the control value is different from those set for the otherreactors, the control value of the flow rate of the diluent gas which issupplied from the third main gas supply path 31 to the specific reactoris set such that the control value is different from those set for theother reactors.

For example, when the control value of the concentration of thegroup-III element and the group-V element in the reactor 10 a is lessthan those in the other three reactors 10 b, 10 c, and 10 d, the controlvalue of the flow rate of gas adjusted by the adjustment mass flow meter134 a among the four adjustment mass flow meters 134 a, 134 b, 134 c,and 134 d increases. The flow rate of the diluent gas supplied to thefifth sub-gas supply path 33 a increases and the control value of theconcentration of the group-III element and the group-V element for thereactor 10 a is less than those for the other reactors 10 b, 10 c, and10 d.

For example, when the control value of the concentration of thegroup-III element and the group-V element for the reactor 10 a isgreater than those for the other three reactors 10 b, 10 c, and 10 d,the control values of the flow rates of gas adjusted by three adjustmentmass flowmeter 134 b, 134 c, 134 d among the four adjustment mass flowmeters 134 a, 134 b, 134 c, and 134 d are greater than the control valueof the flow rate of gas adjusted by the adjustment mass flow meter 134a. The flow rate of the diluent gas supplied to the fifth sub-gas supplypath 33 a decreases and the control value of the concentration of thegroup-III element and the group-V element for the reactor 10 a isgreater than those for the other reactors 10 b, 10 c, and 10 d.

For example, when the control value of the rotation speed of thesemiconductor wafer W1 for a specific reactor is set to be differentfrom those for the other reactors, the control value of the rotationspeed of the rotary driver 114 for the specific reactor is set to bedifferent from those for the other reactors.

For example, when the control value of the temperature of thesemiconductor wafer W1 for a specific reactor is set to be differentfrom those for the other reactors, the control value of power suppliedto the heater 116 for the specific reactor is set to be different fromthose for the other reactors.

The first process gas, the second process gas, and the diluent gas aresupplied to each of the reactors 10 a, 10 b, 10 c, and 10 d by theabove-mentioned method and stacked films in which an InGaN film and aGaN film are alternately stacked are formed on a plurality ofsemiconductor wafers W1 at the same time.

Next, the function and effect of the vapor phase growth apparatus andthe vapor phase growth method according to this embodiment will bedescribed.

When films having the same characteristics are grown on a plurality ofsubstrates at the same time, using a plurality of reactors, the processparameters of the reactors are set to the same control values. When theprocess parameters of the reactors are set to the same control values,it is possible to theoretically grow films having the samecharacteristics on a plurality of substrates at the same time.

In some cases, even if the process parameters of the reactors are set tothe same control values, a variation in the characteristics of the filmsgrown in each reactor occurs. The variation in the characteristics ofthe film is caused by, for example, the difference between the controlvalue of each process parameter and the actual value.

Among the characteristics of the film to be grown, necessarycharacteristics are the thickness and composition of the film. Whenfilms having the same characteristics are grown on a plurality ofsubstrates at the same time, using a plurality of reactors, it isassumed that the processing time of each reactor is constant. In otherwords, the process gas supply start time and the process gas supplyshutoff time are the same in all of the reactors.

Therefore, for example, when there is only the difference in the filmthickness between one reactor and the other reactors, it is necessary tochange only the thickness of the film in the same processing time,without changing the composition of the film, in order to obtain thesame film thickness in the reactors.

When the control value of the flow rate of the process gas supplied to aplurality of reactors is changed for each reactor to independentlycontrol the flow rate of the process gas in each reactor, the structureof the vapor phase growth apparatus becomes complicated, which is notpreferable.

Therefore, it is preferable that the control value of the flow rate ofthe process gas supplied to each reactor is not independently set. Inaddition, it is preferable that the control value of the flow rate ofthe process gas supplied to each reactor is not independentlycontrolled.

FIG. 3 is a diagram illustrating the function and effect of the vaporphase growth apparatus and the vapor phase growth method according tothis embodiment. FIG. 3 is a diagram illustrating the relationship amongthe total flow rate of the process gas, an MQW period, and the indiumcomposition of films when an InGaN film and a GaN film are alternatelygrown to form an MQW.

The InGaN film is formed using a mixed gas (first process gas) of TMGand TMI having nitrogen gas as carrier gas and ammonia (second processgas). The GaN film is formed using TMG (first process gas) havingnitrogen gas as carrier gas and ammonia (second process gas).

The flow rate of the diluent gas is changed to change the total gas flowrate. Therefore, when the total gas flow rate is high, the concentrationof the group-III element and the group-V element which are supplied islow. In contrast, when the total gas flow rate is low, the concentrationof the group-III element and the group-V element which are supplied ishigh.

The MQW period is a total film thickness when one InGaN film and one GaNfilm are formed.

As can be seen from FIG. 3, the dependence of a change in the MQW periodon a change in the total gas flow rate is large and the dependence of achange in the composition of indium in the film on the change in thetotal gas flow rate is small. When the total gas flow rate is changed,the thickness and composition of the film are changed in different ways.Therefore, for example, the flow rate of the diluent gas can be changedto change only the thickness of the film in the same processing time,without changing the composition of the film.

FIG. 4 is a diagram illustrating the function and effect of the vaporphase growth apparatus and the vapor phase growth method according tothis embodiment. FIG. 4 is a diagram illustrating the relationship amongthe rotation speed of the substrate, an MQW period, and the indiumcomposition of films when an InGaN film and a GaN film are alternatelygrown to form an MQW. In FIG. 4, the process gas used to form the filmis the same as that in FIG. 3.

As can be seen from FIG. 4, the dependence of a change in the MQW periodon a change in the rotation speed of the substrate is large and thedependence of a change in the indium composition of the film on thechange in the rotation speed of the substrate is small. When therotation speed is changed, the thickness and composition of the film arechanged in different ways. Therefore, for example, the rotation speedcan be changed to change only the thickness of the film in the sameprocessing time, without changing the composition of the film.

FIG. 5 is a diagram illustrating the function and effect of the vaporphase growth apparatus and the vapor phase growth method according tothis embodiment. FIG. 5 is a diagram illustrating the relationship amongthe temperature of the substrate, an MQW period, and the indiumcomposition of films when an InGaN film and a GaN film are alternatelygrown to form an MQW. In FIG. 5, the process gas used to form the filmis the same as that in FIG. 3.

As can be seen from FIG. 5, the dependence of a change in the MQW periodon a change in the temperature of the substrate is small and thedependence of a change in the indium composition of the film on thechange in the temperature of the substrate is large. When thetemperature of the substrate is changed, the thickness and compositionof the film are changed in different ways. Therefore, for example, thetemperature of the substrate can be changed to change only thecomposition of the film in the same processing time, without changingthe thickness of the film.

The vapor phase growth apparatus and the vapor phase growth methodaccording to this embodiment perform control such that the control valueof at least one process parameter selected from the concentration of thegroup-III element and the group-V element supplied to the reactors, therotation speed of the substrate, and the temperature of the substrate isindependently set for the n reactors and films are formed on thesubstrates in the n reactors at the same time. Therefore, when films areformed on a plurality of substrates in a plurality of reactors, thecharacteristics of the films grown in each reactor can be adjusted so asto be matched with each other.

Second Embodiment

A vapor phase growth apparatus according to this embodiment furtherincludes pressure adjusters which are provided in each of n sub-gasexhaust paths. A controller performs control such that the control valueof pressure is independently set for the n reactors and films are grownon substrates in the reactors at the same time. This is the differencebetween the vapor phase growth apparatus according to this embodimentand the vapor phase growth apparatus according to the first embodiment.

A vapor phase growth method according to this embodiment differs fromthe vapor phase growth method according to the first embodiment in thatthe control value of pressure in at least one of the n reactors is setto be different from the control values of pressure in the otherreactors and films are grown on substrates in the n reactors at the sametime.

The description of the same parts as those in the first embodiment willnot be repeated.

FIG. 6 is a diagram illustrating the structure of the vapor phase growthapparatus according to this embodiment.

The vapor phase growth apparatus according to this embodiment includesfour sub-gas exhaust paths 15 a, 15 b, 15 c, and 15 d that discharge gasfrom four reactors 10 a, 10 b, 10 c, and 10 d. In addition, the vaporphase growth apparatus includes a main gas exhaust path 16 that isconnected to the four sub-gas exhaust paths 15 a, 15 b, 15 c, and 15 d.A vacuum pump 17 for drawing gas is provided in the main gas exhaustpath 16. The vacuum pump 17 is an example of a pump.

Pressure adjusters 18 a, 18 b, 18 c, and 18 d are provided in the foursub-gas exhaust paths 15 a, 15 b, 15 c, and 15 d, respectively. Thepressure adjusters 18 a, 18 b, 18 c, and 18 d adjust the internalpressure of the reactors 10 a, 10 b, 10 c, and 10 d to a predeterminedvalue, respectively. The pressure adjusters 18 a, 18 b, 18 c, and 18 dare, for example, throttle valves.

A controller 19 performs control such that the control value of pressurein the four reactors 10 a, 10 b, 10 c, and 10 d is independently set forthe four reactors 10 a, 10 b, 10 c, and 10 d and films are grown onsubstrates in the four reactors 10 a, 10 b, 10 c, and 10 d at the sametime.

In the vapor phase growth method according to this embodiment, thecontroller 19 sets the pressure control value of at least one of thepressure adjusters 18 a, 18 b, 18 c, and 18 d so as to be different fromthe pressure control values of the other pressure adjusters. Therefore,the controller 19 performs control such that the control value ofpressure in at least one of the four reactors 10 a, 10 b, 10 c, and 10 dis different from the control values of pressure in the other reactors.Then, films are grown on substrates in the four reactors 10 a, 10 b, 10c, and 10 d at the same time.

The vapor phase growth apparatus and the vapor phase growth methodaccording to this embodiment can independently control the internalpressure of the n reactors at the same time. Therefore, when films areformed on a plurality of substrates in a plurality of reactors at thesame time, the characteristics of the films grown in each reactor can beadjusted so as to be matched with each other.

Third Embodiment

A vapor phase growth apparatus according to this embodiment includes afilm thickness measure that can measure the thickness of a film that isbeing grown in a reactor. A controller independently sets at least oneof the control values of the concentration of a group-III element and agroup-V element supplied to the reactor, the rotation speed of asubstrate, and the temperature of the substrate for n reactors, on thebasis of the measurement result of the film thickness by the filmthickness measure during the growth of the film. This is the differencefrom the vapor phase growth apparatus according to the first embodiment.

A vapor phase growth method according to this embodiment differs fromthe vapor phase growth method according to the first embodiment in thatat least one of the control values of the concentration of the group-IIIelement and the group-V element supplied to the reactor, the rotationspeed of a substrate, and the temperature of the substrate for at leastone of the n reactors is changed to a value that is different from thosefor the other reactors, on the basis of the measurement result of thefilm thickness by the film thickness measure during the growth of thefilm, and films are grown on the substrates in the n reactors at thesame time.

The description of the same parts as those in the first embodiment willnot be repeated.

FIG. 7 is a diagram schematically illustrating the reactor of the vaporphase growth apparatus according to this embodiment.

The vapor phase growth apparatus according to this embodiment includes afilm thickness measure 150 that is provided on a shower plate 101. Thefilm thickness measure 150 can measure the thickness of a film that isbeing grown on a wafer W. For example, the film thickness measure 150monitors light interference to measure the thickness of the film that isgrown on the substrate.

The controller 19 (FIG. 1) independently sets at least one of thecontrol values of the concentration of the group-III element and thegroup-V element supplied to four reactors 10 a, 10 b, 10 c, and 10 d,the rotation speed of the wafer W, and the temperature of the wafer Wfor the four reactors 10 a, 10 b, 10 c, and 10 d, on the basis of themeasurement result of the film thickness by the film thickness measure150 during the growth of the film.

In the vapor phase growth method according to this embodiment, thecontroller 19 changes at least one of the control values of theconcentration of the group-III element and the group-V element suppliedto four reactors 10 a, 10 b, 10 c, and 10 d, the rotation speed of thewafer W, and the temperature of the wafer W for at least one of the fourreactors 10 a, 10 b, 10 c, and 10 d to a value that is different fromthe control values for the other reactor, on the basis of themeasurement result of the film thickness by the film thickness measure150 during the growth of the film. Then, films are grown on substratesin the four reactors 10 a, 10 b, 10 c, and 10 d, on the basis of thechanged control value.

The vapor phase growth apparatus and the vapor phase growth methodaccording to this embodiment change the control value of at least oneprocess parameter among the concentration of the group-III element andthe group-V element supplied to the reactors, the rotation speed of thewafer W, and the temperature of the wafer W, on the basis of themeasurement result of the film thickness by the film thickness measure150 during the growth of the film. Then, control is performed such thatfilms are grown on substrates in the n reactors at the same time on thebasis of the changed control value. Therefore, even if it is determinedthat there is an error in the thickness of the film which is beinggrown, a variation in the characteristics of the films between thereactors can be adjusted such that the characteristics of the films arematched with each other.

Fourth Embodiment

A vapor phase growth apparatus according to this embodiment has the samestructure as the vapor phase growth apparatus according to the firstembodiment, but a vapor phase growth method according to this embodimentdiffers from the vapor phase growth method according to the firstembodiment in that the control value of the power of the heater isreduced to stop a deposition process in at least one of n reactors. Thedescription of the same parts as those in the first embodiment will notbe repeated.

In the vapor phase growth method according to this embodiment, similarlyto the first embodiment, a deposition process is performed in advance ona semiconductor wafer W1, which is an example of a substrate, in each offour reactors 10 a, 10 b, 10 c, and 10 d on the basis of the controlvalue of each process parameter.

When a trouble occurs in the reactor 10 a during the deposition processand it is difficult to continuously perform the deposition process, thecontrol value of the power of the heater 116 is reduced to 0 kW to stopthe deposition process while the process gas is flowing and thedeposition process is continuously performed in the reactors 10 b, 10 c,and 10 d without any trouble, similarly to the first embodiment.

As in the vapor phase growth apparatus according to this embodiment, ina case in which a predetermined amount of process gas is distributed andsupplied to the reactors at the same time, when the supply of theprocess gas to the reactor with a trouble is stopped, various problemsarise. Specifically, for example, it is difficult to adjust the flowrate due to the lower limit of the control of the mass flow controller.In addition, a reaction product is accumulated in, for example, anexhaust valve. As a result, gas flows out of the reactor 10 a or gasflows backward from the exhaust valve, due to the outflow (internalleakage) of gas from the valve. Therefore, it is necessary to provide avalve on the exhaust side. In addition, it is necessary to change thetotal flow rate of the process gas and to readjust the control values.Furthermore, since there is a dead space on the upstream pipe side, itis necessary to provide a valve in a branch portion.

However, in this embodiment, even if a trouble occurs in any one of thereactors, the process gas continuously flows to all of the reactors.Therefore, it is possible to prevent the above-mentioned problems.

In this case, even if a trouble occurs in two or more of the reactors,it is possible to continuously perform the deposition process in theother reactors. When the wafer W can be rotated in a reactor with atrouble, the wafer W may be maintained in a rotated state or therotation of the wafer W may be stopped. When the heater can be turnedon, the control value of the power of the heater is not necessarilyreduced to 0 kW in order to stop the formation of a film on the wafer Wand the wafer W may be heated at a low temperature. That is, the controlvalue of the output of the heater may be set to a value which is lessthan the control value in the deposition process and at which a processgas reaction does not occur (for example, 0 kW to 5 kW) to stop theformation of a film. Alternatively, the control value of the temperatureof the substrate is set to the temperature which is less than thecontrol value in the deposition process and at which a process gasreaction does not occur (for example, a room temperature to 300° C.) tostop the formation of a film.

In this embodiment, control is independently performed for the reactorwith a trouble. However, the invention can be applied to a case in whichthere is an odd lot (for example, when one lot includes 25 wafers andthere are four reactors, the remainder is 1). That is, when a new waferW is processed, the control value of the power of the heater 116 in thereactor in which the deposition process is not performed may be set to 0kW or a small value or the control value of the temperature of thesubstrate may be set to a value that is equal to or greater than theroom temperature, while the process gas is flowing to all of thereactors. In this case, it is not necessary to readjust the controlvalues of parameters in the lot and to continuously perform a series ofdeposition processes.

In this case, it is preferable to place a dummy wafer on the supportportion 112 in the reactor in which the deposition process is notperformed, in order to prevent the process gas from flowing into therotary driver.

The embodiments of the invention have been described above withreference to examples. The above-described embodiments are illustrativeexamples and do not limit the invention. In addition, the componentsaccording to each embodiment may be appropriately combined with eachother.

For example, in the above-described embodiments, examples of the processparameters have been described. However, the process parameters are notnecessarily limited to the examples. For example, any process parameterscan be used as long as they can be independently controlled in eachreactor at a predetermined time when the deposition process is performedin the n reactors. That is, process parameters other than time can beused.

For example, when the remainder of the process gas which does not flowto (n−1) sub-gas supply paths is supplied from one sub-gas supply pathto one reactor other than (n−1) reactors, structures other than theembodiments can be used.

For example, in the embodiments, the stacked film in which a pluralityof first nitride semiconductor films including indium (In) and gallium(Ga) and a plurality of second nitride semiconductor films includinggallium (Ga) are stacked on the GaN film is epitaxial grown. However,for example, the invention can be applied to form other group III-Vnitride-based semiconductor single-crystal films, such as aluminumnitride (AlN), aluminum gallium nitride (AlGaN), and indium galliumnitride (InGaN) single-crystal films. In addition, the invention can beapplied to a group III-V semiconductor such as GaAs.

In the above-described embodiments, hydrogen gas (H₂) is used as thecarrier gas. However, nitrogen gas (N₂), argon gas (Ar), helium gas(He), or a combination of the gases can be applied as the carrier gas.

In the above-described embodiments, the process gases are mixed in theshower plate. However, the process gases may be mixed before they flowinto the shower plate. In addition, the process gases may be in aseparated state until they are ejected from the shower plate into thereactor.

In the above-described embodiments, the epitaxial apparatus is thevertical single wafer type in which the deposition process is performedfor each wafer in the n reactors. However, the application of the nreactors is not limited to the single-wafer-type epitaxial apparatus.For example, the invention can be applied a horizontal epitaxialapparatus or a planetary CVD apparatus that simultaneously forms filmson a plurality of wafers which revolve on their own axes and around theapparatus.

In the above-described embodiments, for example, portions which are notnecessary to describe the invention, such as the structure of theapparatus or a manufacturing method, are not described. However, thenecessary structure of the apparatus or a necessary manufacturing methodcan be appropriately selected and used. In addition, all of the vaporphase growth apparatuses and the vapor phase growth methods whichinclude the components according to the invention and whose design canbe appropriately changed by those skilled in the art are included in thescope of the invention. The scope of the invention is defined by thescope of the claims and the scope of equivalents thereof.

What is claimed is:
 1. A vapor phase growth apparatus comprising: n (nis an integer equal to or greater than 2) reactors performing adeposition process for a plurality of substrates at the same time; afirst main gas supply path distributing a predetermined amount of firstprocess gas including a group-III element and supplying the firstprocess gas to the n reactors at the same time; a second main gas supplypath distributing a predetermined amount of second process gas includinga group-V element and supplying the second process gas to the n reactorsat the same time; a controller controlling a flow rate of the firstprocess gas and a flow rate of the second process gas, on the basis ofcontrol values of flow rates of the first process gas and the secondprocess gas supplied to the n reactors, the controller independentlycontrolling at least one predetermined process parameter in the nreactors, on the basis of control values of the at least onepredetermined process parameter independently set for each of the nreactors; a rotary driver provided in each of the n reactors androtating each of the plurality of substrates; and a heater provided ineach of the n reactors and heating each of the plurality of substrates.2. The vapor phase growth apparatus according to claim 1, wherein the atleast one predetermined process parameter is selected from concentrationof the group-III element and the group-V element in process gas suppliedto the n reactors, rotation speed of the substrates, temperature of thesubstrates, output of the heater, and internal pressure of the reactors.3. The vapor phase growth apparatus according to claim 1, wherein thecontroller performs control such that an operation of starting the firstprocess gas supply, an operation of shutting off the first process gassupply, an operation of starting second process gas supply, and anoperation of shutting off of the second process gas supply are performedin the n reactors at the same time.
 4. The vapor phase growth apparatusaccording to claim 2, further comprising: n diluent gas supply linessupplying a diluent gas to the n reactors, wherein the controllercontrols amount of diluent gas supplied, on the basis of the controlvalues of the concentration of the group-III element and the group-Velement, the control values being independently set for the n reactors.5. The vapor phase growth apparatus according to claim 1, wherein eachof the n reactors includes a film thickness measure capable of measuringa thickness of a film being grown, and the controller changes andadjusts the at least one of the control values of the at least onepredetermined process parameter independently for the n reactors, on thebasis of a measurement result of film thickness by the film thicknessmeasure during growth of the film.
 6. The vapor phase growth apparatusaccording to claim 1, wherein the controller includes a calculatorcalculating the control values of the at least one predetermined processparameter from information about correlation between characteristics offilms obtained in the n reactors and the at least one predeterminedprocess parameter in advance and the characteristics of the filmsobtained in the n reactors in advance.
 7. The vapor phase growthapparatus according to claim 1, further comprising: n sub-gas exhaustpaths connected to the n reactors and discharging gas from the nreactors; n pressure adjusters connected to the n sub-gas exhaust path;a main gas exhaust path connected to the sub-gas exhaust paths; and avacuum pump connected to the main gas exhaust path.
 8. The vapor phasegrowth apparatus according to claim 7, wherein the controllerindependently sets pressure control values of the n pressure adjuster.9. A vapor phase growth method comprising: loading a plurality ofsubstrates to n reactors; distributing a predetermined amount of firstprocess gas including a group-III element and starting the first processgas supply to the n reactors at the same time at a flow rate controlledon the basis of control values of a first flow rate; distributing apredetermined amount of second process gas including a group-V elementand starting second process gas supply to the n reactors at the sametime at a flow rate controlled on the basis of control values of asecond flow rate; controlling independently at least one predeterminedprocess parameter of the n reactors, on the basis of control values ofthe at least one predetermined process parameter, and growing films onthe plurality of substrates in the n reactors at the same time; shuttingoff the first process gas supply to the n reactors at the same time; andshutting off the second process gas supply to the n reactors at the sametime.
 10. The vapor phase growth method according to claim 9, furthercomprising: loading a plurality of test substrates to the n reactors,distributing the predetermined amount of the first process gas andstarting the first process gas supply to the n reactors at the same timeat the flow rate controlled on the basis of the control value of thefirst flow rate, distributing the predetermined amount of second processgas and starting the second process gas supply to the n reactors at thesame time at the flow rate controlled on the basis of the control valueof the second flow rate, controlling the at least one predeterminedprocess parameter on the basis of initial control values of the at leastone predetermined process parameter, and growing films on the pluralityof test substrates in the n reactors at the same time, shutting off thefirst process gas supply to the n reactors at the same time, shuttingoff the second process gas supply to the n reactors at the same time,measuring characteristics of the films grown on the plurality of testsubstrates, and calculating the control values of the at least onepredetermined process parameter of the n reactors on the basis of themeasured characteristics of the films.
 11. The vapor phase growth methodaccording to claim 9, wherein the at least one predetermined processparameter is selected from concentration of the group-III element andthe group-V element in process gas supplied to the n reactors, rotationspeed of the substrates, temperature of the substrates, power of heaterprovided in each of the n reactors, and internal pressure of thereactors.
 12. The vapor phase growth method according to claim 11,wherein the at least one predetermined process parameter is the power ofthe heater or the temperature of the substrates, and during the growingfilms, stop the growth of the film in at least one of the n reactors,the control value of the power of the heater or the temperature of thesubstrates in the at least one of the n reactors is set to be less thana control value when the film is grown on the substrate.
 13. The vaporphase growth method according to claim 9, wherein the film is a stackedfilm of an indium gallium nitride film and a gallium nitride film. 14.The vapor phase growth method according to claim 13, wherein the atleast one predetermined process parameter is the rotation speed of thesubstrate.
 15. The vapor phase growth method according to claim 13,wherein the at least one predetermined process parameter is temperatureof the substrates.